FAQ

The installation of an electricity meter and a heat meter is mandatory in order to qualify for public subsidies. The electricity meter must measure the total electricity consumption of the heat pump (including additional consumers such as the circulation pump and radiators). The heat meter must indicate the amount of heat produced.

This data can be used to determine whether the installation is operating efficiently and, in the event of faults, to call in a specialist quickly.

If the heat pump control system is capable of displaying the data, external installation of components is not necessary.

Yes, geothermal probes also allow you to use a heat pump to cool a building. It is even advisable, as the heat extracted from the house can be used to regenerate the ground.

In this context, a distinction must be drawn between active and passive cooling. In an active system, the heat pump acts as a cooling unit during the summer by actively reversing the circulation within the pump. In a passive system, on the other hand, the heat exchanger is used to evacuate the heat from the dwelling to the probe circuit. Passive cooling is recommended due to the high electricity consumption of an active system.

It is recommended that the drilling work only be performed by a company with DVGW W 120 certification (ADEME-BRGM-EDF quality commitment approach) or equivalent. If the work is not carried out by a competent company, drilling and probe installation work can lead to serious complications, both during the drilling work itself and during subsequent operation. It is also essential to have a sound knowledge of Luxembourg geology.

Find out about this from the drilling company you have chosen.

No. Boreholes drilled for surface geothermal energy cannot under any circumstances trigger an earthquake. Nor has a geothermal probe ever been observed to have been damaged by an earthquake.

Under the new rules for the installation of geothermal probes, damage can be practically excluded if the rules are carefully observed.

The operator of a facility – in this case, you as an individual – is liable for the construction and operation of the facility in compliance with the applicable provisions and for all damages that may result therefrom. You should therefore check carefully that the drilling documents are complete. These should include:

the completed pressure test form as proof of the tightness of the geothermal probe once the probe has been placed (ask the drilling company if this report complies with VDI Guideline 4640);
the complete drilling report.

No. The Law of 19 December 2008 on water prohibits the direct or indirect discharge of water as well as other solid or gaseous substances. Groundwater heat pumps cannot therefore be authorised in Luxembourg.

The COP value is an important indicator for comparing the efficiency of heat pumps. The coefficient of performance (COP) measures the efficiency of a heat pump. Specifically, the COP value that dealers put on their devices indicates the ratio of thermal power to the drive energy (electricity) needed to generate it. This efficiency is determined on the basis of theoretical calculations or under specific test conditions. 

As a general rule:

• ground source heat pump glycol/water: COP ≥ 4.3 at B0/W35;
• air/water heat pump (including exhaust air/water heat pump): COP ≥ 3.1 at A2/W35

in accordance with standard EN 14511.

Please note: performance figures are not necessarily indicative of the overall annual efficiency of the heat pump system. The annual coefficient of performance (ACOP) shows the ratio of annual heating energy production to drive and auxiliary energy consumption. It thus provides a clear picture of the efficiency of the system as a whole, including the auxiliary energy consumed, for example, by the heat pump and the brine circulation pump. It is therefore always necessary to determine the annual coefficient of performance for the installation site and the building in question. As a customer, always insist that this coefficient be calculated!

The size of the installation must be calculated in accordance with VDI (Association of German Engineers) Guideline 4640. Ask your chosen drilling company for information on this subject.
In addition, you can also have a heat load calculation and a geological survey carried out in order to establish the sizing.

You must ensure that you have obtained all necessary permits before the works start. Contact : forages@eau.etat.lu

The exact date of the start of drilling must then be notified to the water management authority in advance. Ensure that the drilling company and the installer coordinate their schedules.

Plan appropriate access to the site in advance.